The invention described herein may be manufactured and used by or for the Government of the United States of America for Governmental purposes without the payment of any royalties thereon or therefor.
(1) Field of the Invention
The present invention relates generally to patch antennas, and more particularly to a microstrip patch antenna having a plurality of parallel slots formed therein to increase the bandwidth performance of the antenna.
(2) Description of the Prior Art
An ordinary microstrip patch antenna consists of a rectangular metallic xe2x80x9cpatchxe2x80x9d that is printed on top of a grounded slab of dielectric material. It is a very useful antenna, but suffers from limited bandwidth as a result of its resonant properties. Bandwidth of these antennas is typically limited to 2-4% of the antenna""s center frequency.
Accordingly, it is an object of the present invention to provide a patch antenna having improved bandwidth characteristics.
Another object of the present invention is to provide a rectangular microstrip patch antenna having improved bandwidth characteristics for a variety of antenna applications.
Other objects and advantages of the present invention will become more obvious hereinafter in the specification and drawings.
In accordance with the present invention, a patch antenna with progressive slot loading is based on a rectangular patch of electrically conductive material with long and short dimensions. A centerline of the patch is defined along the long dimension. The patch has a feedpoint located at one end of the patch at its centerline. A plurality of slots are formed in the patch with each slot having its center aligned with the centerline of the patch. Further, each slot has its longitudinal axis perpendicular to the centerline of the patch. Each slot has a unique length Ln and width Wn. The slots are arranged in an order starting at a position n=1 that is furthest from the patch""s feedpoint so that, for an n-th slot, the inequalities Ln greater than Ln+1 and Wn less than Wn+1 are always satisfied. In general, the length decreases linearly with each successive slot while the width increases exponentially with each successive slot.